Common Rail Valve Seat Refurbishing Tool and Apparatus

ABSTRACT

A tool and apparatus to refurbish a valve seat having a compound geometry, such as a valve seat in a valve body for a common rail fuel injector is disclosed. The tool includes a body with a head portion having substantially the same geometry as the valve seat to be refurbished. The tool further includes a radiused portion located between two angled surfaces of the tool that functions to provide a chamfered cut at the intersection of the valve seat and diffuser passage to be refurbished. The apparatus includes a collet to secure the tool, and the collet may be mounted or secured to a fixture which is in turn mounted on a preloaded biased base so movement of the tool in the Z axis is controllable. The apparatus also comprises a slide moveable in an X and Y axis for adjustment of the tool.

CROSS-REFERENCE TO RELATED APPLICATIONS

The following continuation application claims the benefit of U.S. patentapplication Ser. No. 13/433,481, filed on Mar. 29, 2012, which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

In a common rail fuel injector, a high pressure valve seat is used tocontrol injector firing. When a magnetic energizer energizes, anarmature lifts and a ball lifts from its seat. High pressure fuel (up to2000 bar) spills out of a control chamber at elevated velocities betweenthe ball and the valve seat. The lift of the ball is only in the orderof about fifty (50) microns, and this creates extreme fuel velocities,which make the area prone to cavitation. To address this issue,manufacturers have provided a small relief angle called a diffuser anglebelow the valve seat to help smooth the fluid flow past the ball/valveseat while the injector is firing.

It has been a challenge in the remanufacturing of valve seats of commonrail fuel injectors to provide for consistent stock removal between thevalve seat and the diffuser angle. Typical approaches included lappingthe valve seat, which only serves to reduce the effective diffuserdiameter, which in turns increases the rate of cavitation. Lapping thevalve seat and the diffuser angle separately presents extreme challengesin maintaining the diffuser diameter within acceptable tolerances.

Thus, there is a need for a tool and an apparatus to lap the valve seatand maintain the diffuser diameter within acceptable tolerances inrefurbishment of common rail fuel injectors.

SUMMARY

In one embodiment, the disclosure relates to a lapping tool to refurbisha valve seat having a compound geometric profile. The tool includes abody having a length and a width wherein the length may be greater thanthe width. The body so defined has a first end and a second end inopposed relation to each other. The first end is insertable into a unitfor lapping tool motion in an X axis, a Y axis and a Z axis. The secondend terminates in a head portion. The head portion may be equipped withan abrasive surface and has a compound geometric profile substantiallythe same as the compound geometric profile of the valve seat and alsoincludes a radiused portion at the intersection of the compoundgeometric profile to create a chamfered surface. The tool is rotated atvarious speeds to facilitate refurbishing of the valve seat in a singleaction.

In another embodiment, the disclosure relates to a lapping tool torefurbish a valve having a valve seat angle and a diffuser angle. Thetool includes a body having a length greater than a width and opposedfirst and second ends. The first end is configured to be insertable in alapping unit for motion of the tool in an X axis, a Y axis and a Z axis.The second end is equipped with a head portion having an abrasivesurface. The head portion is configured to have a head valve seat angleand a head diffuser angle separated by a radiused portion. The headportion valve seat angle is of substantially the same angle as the valveseat angle, and the head portion diffuser portion angle is ofsubstantially same angle as said valve seat diffuser angle. The headradiused portion forms a chamfered intersection between said valve seatangle and said valve seat diffuser angle to maintain the diameter of therefurbished diffuser.

In another embodiment, the disclosure relates to an apparatus torefurbish a ball check valve in a single operation. The apparatus may bea computer numerically controlled machining center, including a fixtureconfigured to accept a ball check valve. The fixture is mountable in anprecision slide machining apparatus for movement of the fixture in an Xaxis and a Y axis, and the fixture is supported by a preloaded biaser,such as, for example a spring, to control movement of the fixture in a Zaxis. The apparatus may also include a rotary power unit suitable torotate a lapping tool at various speeds. The lapping tool may beequipped with a body having a length greater than a width and opposedfirst and second ends. The first end is insertable in a lapping unit formotion of the tool in an X axis, a Y axis and a Z axis, and the secondend is equipped with a head portion having an abrasive surface. The headportion has a valve seat angle and a diffuser angle separated by aradiused portion. The head portion valve seat angle of substantially thesame angle as the valve seat angle, and the head portion diffuserportion angle of substantially same angle as said valve seat diffuserangle. The head portion also includes a radiused portion forming achamfered intersection between said head portion valve seat angle andsaid head portion valve seat diffuser angle.

These and other aspects of the disclosure will be apparent upon areading of the specification and consideration of the drawings andclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a common rail fuel injectorcomprising a ball check valve;

FIG. 2A is a detailed view of Section 2A of FIG. 1 illustrating the ballcheck valve in the common rail fuel injector;

FIG. 2B is a cut way side view of the ball check valve of FIG. 2Ashowing its construction;

FIG. 2C is a detailed view of Section 2C of FIG. 2B illustrating thevalve seat of the ball check valve;

FIG. 2D is a detailed view of Section 2C of FIG. 2B detailing thediffuser passage, diffuser distance, and diffuser angle of the ballcheck valve;

FIG. 3A is a side view of one embodiment of a lapping tool according tothe disclosure;

FIG. 3B is a detailed view of Section 3B of FIG. 3A illustrating thehead portion of the lapping tool;

FIG. 3C is a detailed view of Section 3B of FIG. 3A illustrating theangled surfaces of the lapping tool;

FIG. 4 is a sectional representation of one apparatus according to thedisclosure; and

FIGS. 5 through 9 are photomicrographs showing the machined valve seatand diffuser surfaces after various test times to simulate actual usewear.

DETAILED DESCRIPTION

Turning now to the drawings wherein like numbers refer to likestructures, FIG. 1 is a representation of a common rail fuel injector10. While there are many parts and assemblies that comprise the commonrail fuel injector 10, the description will be only to those portions ofthe common rail fuel injector 10 that are relevant to the inventiveconcepts of the present application, inasmuch as common rail fuelinjectors are well known to those skilled in the art and need not bedescribed in great detail here.

Referring still to FIG. 1, the common rail fuel injector 10 has a bodyportion 12 upon which is situated a nozzle portion 14 at one endthereof, and a magnetic energizer 16 at the opposite end. The energizer16 is electronically connected to an Electronic Control Unit (ECU) (notshown) and energized as per fueling instructions held in memory of theECU to permit fuel to pass through the injector and out of the nozzle14. In this regard, fuel is introduced under pressure through intakefuel passage 18, where it encounters ball check valve 30 in valve body20. The ball check valve body 20 has a valve seat 22 and a diffuserpassage 38. A bearing 24, which may be a ball for example, sits on abearing seat 32 and obstructs diffuser passage 38. The valve body 20 iscomposed at least partially of a magnetic material such that when themagnetic energizer 16 is energized, ball check valve 30 is attracted outof engagement from the surface of the valve seat 22. When the ball checkvalve 30 is disengaged from its valve seat 22, the pressurized fueldisplaces bearing 24 from its bearing seat 32, permitting thepressurized fuel to enter the diffuser passage 38 and flow to the highpressure fuel passage 28. The fuel flowing through the high pressurefuel passage 28 causes needle 15 in the nozzle 14 to lift, therebyallowing fuel to be injected into the engine through apertures (notshown).

Turning now to FIG. 2A, there is shown a detailed view of Section 2A ofFIG. 1 illustrating the ball check valve 30 in the common rail fuelinjector 10. With greater reference to valve body 20, magnetic energizer16 is in close proximity to ball check valve 30. The valve body 20 has acompound geometry, with a first surface being a valve seat 22 having avalve seat angle θ. Bearing 24 is seated atop diffuser passage 38 atbearing seat 32. At the intersection of the diffuser passage 38 and thebearing seat 32, valve body 20 has a second surface having a diffuserangle Φ.

FIG. 2B is a cutaway view of the valve body 20 of FIG. 2A. Specifically,the ball check valve 30 sits in a valve seat 22, which has a compoundgeometric profile of a first inclined surface at a valve seat angle θand a second inclined surface at a diffuser angle Φ. As previouslynoted, the bearing 24 is seated atop a diffuser passage 38 at bearingseat 32. When the ball check valve 30 is attracted by the magneticenergizer 16, highly pressurized fuel travels into the valve body 20along the valve seat 22 and displaces the bearing 24 from bearing seat32 to permit the flow of high pressure fuel into the diffuser passage 38and then into the high pressure fuel passage 28. It should be understoodthat the bearing 24 is displaced from the bearing seat 32 only a slightamount, on the order of about fifty (50) microns, and the fuel is undersuch high pressure that, as the fuel travels along the valve seat 22 andinto diffuser passage 38, cavitation occurs along those surfaces suchthat accuracy of the injection event is eventually compromised.Refurbishing of these surfaces is necessary to restore the common railfuel injector 10 to its operating specification.

Turning now to FIGS. 2C and 2D, there is shown a detail of Section 2Cfrom FIG. 2B of the valve body 20. Specifically, valve seat 22 is shownat a valve seat angle θ, and diffuser passage 38 is shown at a diffuserangle Φ. The diffuser angle Φ surrounds and intersects the diffuserpassage 38 to define the ball or bearing seat 32. It is the bearing seat32 that suffers most from cavitation as the fuel passes along the valveseat 22 through the diffuser passage 38 and into the high pressure fuelpassage 28 of the common rail fuel injector 10. It is understood thatthe sharp angled intersection between the diffuser passage 38 and thevalve seat 22 causes especially high pressure flow that contributes tocavitation.

FIG. 3A is a side view of a lapping tool 42 according to one aspect ofthe disclosure. The lapping tool 42 has a body 44 having a length 46 anda width 47 through which an axis of rotation 48 may extend. The length46 of the lapping tool 42 is shown greater than its width 47. The body44 has opposing first and second ends, 45 and 49 respectively. The firstend 45 is insertable into a rotary power unit 66 for rotary motion ofthe lapping tool 42 along its axis of rotation 48. The second end 49comprises a head portion 50, which is better understood with referenceto FIGS. 3B and 3C.

Referring now to FIGS. 3B and 3C, detailed views of Section 3B of FIG.3A are shown illustrating the head portion 50 of the lapping tool 42. Atapered portion 52 separates the body 44 of the lapping tool 42 from thehead portion 50. The head portion 50 comprises an angled work portion 54that extends at a first angle θ₁, which may be conical, parabolic,semi-spherical, or any other shape desired to refurbish the valve seat22 of the valve body 20. The angled work portion 54 includes a worksurface 60, which may be equipped with abrasive material 62 to removematerial from the valve seat 22 of the valve body 20 during a lappingmotion. The abrasive material 62 may be at least one of diamond, cubicboron or silicon carbide, or any other suitable abrasive, and has a gritsufficient to refurbish the valve seat 22 of the valve body 20. In oneembodiment, the grit may be on the order of thirty (30) microns.

Concentric on head portion 50 at its distal end 59 is angled enddiameter portion 58, which extends a sufficient distance 56 to machinethe diffuser passage 38. The angled end diameter portion 58 has a worksurface 61 that extends in a second angle Φ₁. Angled end diameterportion 58 extends at second angle Φ₁ from proximal diameter 90 todistal diameter 92. The first angle θ₁ of the angled work portion 54 issubstantially the same angle as the valve seat angle θ of valve seat 22,and the second angle Φ₁ of the angled end diameter portion 58 of lappingtool 42 is substantially the same angle as the diffuser angle Φ of thediffuser passage 38. It is important to note that a radiused portion 63exists at the intersection between the angled work portion 54 and theangled end diameter 58. Radiused portion 63 is slightly radiused.Accordingly, it can be readily understood that the angled work portion54 and the angled end diameter portion 58 of the head portion 50 do notintersect each other, but rather each one intersects the radiusedportion 63.

Abrasive material 62 may be deposited on the head portion 50 by mixingthe abrasive with a plating material, such as nickel, and overlaying thehead portion 50. This plating will also form the radiused portion 63.The radiused portion 63 can also be formed by forming it when the headportion 50 is formed, and then overlaying it with the abrasive, or inany other way that may be apparent to those skilled in the art.

FIG. 4 is a schematic representation of an apparatus 64 to refurbishvalve seats according to one aspect of this disclosure. Specifically,the lapping tool 42 is fixed or inserted at its first end 45 into rotarypower unit 66 for variable speed rotation of the lapping tool 42. Acollet 72 or a suitable chuck secures the valve body 20 in place. Thecollet 72 is in turn mounted or secured to a fixture, or floatingassembly 68. Floating assembly 68 is floatably mounted on a preloadedbiaser 78, such as a coil spring, leaf springs, resilient material, ahydraulic or pneumatic cylinder arrangement, or any other arrangementthat may control the movement of the floating assembly 68 in the Z axisdirection. The floating assembly 68 is mounted on a slide 67 formovement of the collet 72 and floating assembly 68 in the X axis and theY axis. When it is desired to refurbish a valve seat having a compoundgeometric profile (as described above) the valve body 20 is mounted inthe collet 72 which is then placed in the floating assembly 68. Thelapping tool 42 may be inserted into rotary power unit 66 for rotarymotion at various speeds to provide lapping of the valve seat in asingle operation. The rotary power unit 66 is lowered until the lappingtool 42 contacts the valve seat 22. The lapping tool 42 is then rotatedat a relatively high speed for stock removal of the valve seat 22 for atime sufficient to remove sufficient stock to remove traces ofcavitation, and then at a low speed to improve valve seat roundness.Because the head portion 50 of the lapping tool 42 includes the radiusedportion 63 that finishes the diffuser passage 38, the valve seat 22 andthe diffuser passage 38 may be refurbished in a single action. Thepreloaded biaser 78 prevents over machining in the Z axis, as it ispreloaded and will only permit the correct force be applied in the Zaxis, as it will bias the lapping tool 42 in the opposite Z axisdirection if the tool is plunged too deeply into the valve body 20. Theslide 67 is adapted to provide movement of the floating assembly 68 andcollet 72 in the X axis and the Y axis, to allow for lapping of thevalve seat 22 to ensure complete removal of stock that may have beenaffected by cavitation. Generally, the valve seat 22 is subjected tostock removal at tool rotary speeds up to about 2000 RPM untilcavitation is removed, and then it is subjected to valve seat roundingat tool rotary speed of up to about 150 RPM. All machining aspectsdescribed above, such as the lowering of the rotary power unit 66 tocontact the valve seat 22, activation of the lapping tool 42 forlapping, and adjustment of tool speed, may be controlled by a ComputerNumerically Controlled (CNC) machine center 79.

The lapping tool 42 and apparatus 64 create a refurbished valve body 20that has a chamfered undercut at the bearing seat 32. The chamferedundercut portion is created by the tool head portion 50 where the angledwork portion 54 radiuses into the angled end diameter portion 58 (i.e.,the radiused portion 63 of the head portion 50). The creation of thechamfered cut reduces fuel flow forces during injector use therebyreducing cavitation. In addition, the diameter of the diffuser passage38 is not changed because of the chamfer cut, and the common rail fuelinjector 10 can be restored to specification and remain in service forextended periods between refurbishment.

Table 1 shows that the refurbished injectors were tested for four pointsaccording to Original Equipment Manufacturer (OEM) specifications. Thetable contains data that is illustrative, but not limiting, of theconcepts in this disclosure. Table 1 shows several test examples ofvalve seat bodies refurbished with one embodiment of the describedlapping tool 42 in one embodiment of the apparatus 64 as describedabove.

TABLE 1 Cycle 2VolumeHE Sample Type Part Type Model Date Time Part No.PASS Time Emissions 2SpillFlow 2RailPress After 512 Hours 1 ProductInjector 1B May 4, 2010 13:16 A 647 070 TRUE 265 19.2418 12 807 ProductInjector 1B Aug. 11, 2010  9:34 A 647 070 TRUE 263 19.4377 9 800 0.1959−3 −7 2 Product Injector 1B May 4, 2010 12:48 A 647 070 TRUE 263 19.07918 807 Product Injector 1B Aug. 11, 2010  9:28 A 647 070 FALSE 26219.1645 8.625 797 0.0856 −9.375 −10 3 Product Injector 1B May 4, 201013:11 A 647 070 TRUE 263 19.8474 11.25 793 Product Injector 1B Aug. 11,2010  9:50 A 647 070 FALSE 263 21.0375 10.125 795 1.1901 −1.125 2 4Product Injector 1B May 4, 2010 12:59 A 647 070 TRUE 263 19.8593 9.75804 Product Injector 1B Aug. 11, 2010  9:44 A 647 070 FALSE 262 20.78.625 794 0.8407 −1.125 −10 5 Product Injector 1B May 4, 2010 13:27 A647 070 TRUE 263 18.3416 12 795 Product Injector 1B Aug. 11, 2010  9:39A 647 070 TRUE 263 18.5956 7.5 800 0.254 −4.5 4 AVG 0.51326 −3.825 FieldTolerance 1.8 (+/−) Cycle 3VolumeHE Sample Type Part Type Model DateTime Part No. PASS Time Pilot 3SpillFlow 3RailPress After 512 Hours 1Product Injector 1B May 4, 2010 13:16 A 647 070 TRUE 265 0.8754 8.25 796Product Injector 1B Aug. 11, 2010  9:34 A 647 070 TRUE 263 0.9944 6 7920.119 −2.25 −4 2 Product Injector 1B May 4, 2010 12:48 A 647 070 TRUE263 1.2697 15.75 795 Product Injector 1B Aug. 11, 2010  9:28 A 647 070FALSE 262 1.8517 7.125 804 0.582 8.625 9 3 Product Injector 1B May 4,2010 13:11 A 647 070 TRUE 263 1.2374 7.5 800 Product Injector 1B Aug.11, 2010  9:50 A 647 070 FALSE 263 1.9547 8.25 802 0.7173 0.75 2 4Product Injector 1B May 4, 2010 12:59 A 647 070 TRUE 263 1.4629 7.5 797Product Injector 1B Aug. 11, 2010  9:44 A 647 070 FALSE 262 2.3531 5.625798 0.8902 −1.875 1 5 Product Injector 1B May 4, 2010 13:27 A 647 070TRUE 263 1.0997 9.75 796 Product Injector 1B Aug. 11, 2010  9:39 A 647070 TRUE 263 1.3048 6 802 0.2051 −3.75 6 AVG 0.50272 3.15 FieldTolerance 1 (+/−) Cycle 4VolumeH Sample Type Part Type Model Date TimePart No. PASS Time Idle 4SpillFlow 4RailPress After 512 Hours 1 ProductInjector 1B May 4, 2010 13:16 A 647 070 TRUE 265 4.5918 4.8 252 ProductInjector 1B Aug. 11, 2010  9:34 A 647 070 TRUE 263 5.45 3.375 249 0.8582−1.425 −3 2 Product Injector 1B May 4, 2010 12:48 A 647 070 TRUE 2635.1475 5.25 251 Product Injector 1B Aug. 11, 2010  9:28 A 647 070 FALSE262 5.7999 4.5 251 0.6524 −0.75 0 3 Product Injector 1B May 4, 201013:11 A 647 070 TRUE 263 5.47 3.9375 251 Product Injector 1B Aug. 11,2010  9:50 A 647 070 FALSE 263 5.9774 3.9375 250 0.5074 0 −1 4 ProductInjector 1B May 4, 2010 12:59 A 647 070 TRUE 263 5.7541 4.6875 253Product Injector 1B Aug. 11, 2010  9:44 A 647 070 FALSE 262 6.3754 4.5250 0.6213 −0.1875 −3 5 Product Injector 1B May 4, 2010 13:27 A 647 070TRUE 263 4.4084 4.5 248 Product Injector 1B Aug. 11, 2010  9:39 A 647070 TRUE 263 5.2133 3.75 247 0.8049 −0.75 −1 AVG 0.68884 −0.6225 FieldTolerance 1.3 (+/−) Cycle 5VolumeHE 5SpillFlow Sample Type Part TypeModel Date Time Part No. PASS Time Full Load Spill Flow 5RailPressureAfter 512 Hours 1 Product Injector 1B May 4, 2010 13:16 A 647 070 TRUE265 57.5556 31.75 1594 Product Injector 1B Aug. 11, 2010  9:34 A 647 070TRUE 263 58.2463 26.125 1599 0.6907 −5.625 5 2 Product Injector 1B May4, 2010 12:48 A 647 070 TRUE 263 57.2882 46 1593 Product Injector 1BAug. 11, 2010  9:28 A 647 070 FALSE 262 57.506 31 1598 0.2578 −15 5 3Product Injector 1B May 4, 2010 13:11 A 647 070 TRUE 263 57.0978 38.6251592 Product Injector 1B Aug. 11, 2010  9:50 A 647 070 FALSE 263 57.760736.875 1598 0.06629 −1.75 6 4 Product Injector 1B May 4, 2010 12:59 A647 070 TRUE 263 58.5119 32.25 1596 Product Injector 1B Aug. 11, 2010 9:44 A 647 070 FALSE 262 59.3291 29.75 1600 0.8172 −2.5 4 5 ProductInjector 1B May 4, 2010 13:27 A 647 070 TRUE 263 57.2871 36.5 1593Product Injector 1B Aug. 11, 2010  9:39 A 647 070 TRUE 263 58.057328.625 1595 0.7702 −7.875 2 AVG 0.063176 −6.55 Field Tolerance 2.5 61Max (+/−)

FIGS. 5-9 are photomicrographs showing the bearing seat 32 of theseveral refurbished valve seat bodies after various lengths of service,as described in Table 1. In each instance, as described in the data ofTable 1, cavitation at the bearing seat 32 is substantially diminishedand practically nonexistent. The bearing seat 32 remains functionalwithin specification and the radiused portion clearly demonstrates theadvantage of reduced fuel flow velocities with resultant decreasedcavitation. In addition, the valve body 20 has an increased service lifebetween refurbishments, resulting in substantial savings to an operator.

Specifically, FIG. 5 is a photomicrograph of sample 1, machined andtested as set forth in Table 1. FIG. 5 shows light cavitation at thechamfer (radiused portion)/seat intersection. There was no progressionof cavitation into the ball sealing area 57 of bearing seat 32. There isalso exhibited a very consistent wear pattern with the core material.The ball sealing area 57 shows normal wear after more than 512 hours oftesting.

FIG. 6 is a photomicrograph of sample 2, machined and tested as testforth in Table 1. The figure shows heavier cavitation at thechamfer/seat intersection. However, there is no progression ofcavitation into the ball sealing area 57, and the core material showsvery consistent wear pattern. In addition, the ball sealing area 57shows normal wear, after being machined and tested as set forth in Table1.

FIG. 7 is a photomicrograph of Sample 3, machined and tested as setforth in Table 1. It can be seen that light cavitation occurred at thechamfer/seat intersection, with no progression into the ball sealingarea 57. The core material also showed very consistent wear pattern, andthe ball seating area 57 shows normal wear, after machining and testingas set forth in Table 1.

FIG. 8 is a photomicrograph of sample 4, machined and tested as setforth in Table 1. Again, there is no progression of cavitation into theball sealing area 57, and the core material shows very consistent wearpattern. The ball sealing area 57 shows higher than average wear, butthat wear is still consistent with the core material.

FIG. 9 is a photomicrograph of sample 5, machined and tested as setforth in Table 1. The sample shows a light cavitation at thechamfer/seat intersection, with no progression of cavitation into theball sealing area 57. The core material shows a very consistent wearpattern and the ball sealing area 57 shows normal wear.

Many modifications and variations of the invention as described arepossible in light of the above teachings. In addition, the words used inthe specification are of description, not limitation. Within the scopeof the appended claims, the invention may be practiced other than asspecifically described.

What is claimed as new and desired to be protected by Letters Patent ofthe United States is:
 1. A lapping tool to refurbish a valve seat havinga compound geometric profile, said lapping tool comprising: a bodyhaving a length and a width; said length longer than said width; saidbody having a first end and a second end, said first and second endsopposed to each other; said first end insertable into a unit for lappingtool motion in an X axis, a Y axis and a Z axis; said second endterminating in a head portion, said head portion equipped with anabrasive surface; and said head portion comprising: an angled workportion extending at a first angle, said first angle substantiallycomplimentary to said compound geometric profile of said valve seat; anangled end diameter portion protruding outward from said angled workportion at a second angle, said angled end diameter having a proximaldiameter and a distal diameter, said distal diameter shorter than saidproximal diameter, said angled end diameter portion extending at saidsecond angle from said proximal diameter to said distal diameter; and aradiused head portion separating and contiguous with said angled workportion and said angled end diameter portion.
 2. The lapping tool ofclaim 1, wherein said body and said head portion are separated by atapered portion.
 3. The lapping tool of claim 1, wherein said abrasivesurface includes at least one of diamond, cubic boron, or siliconcarbide abrasive having a grit in the range of about 30 microns.
 4. Thelapping tool of claim 3, wherein said head portion comprises a nickelplated layer with said grit impregnated in said nickel plated layer. 5.A lapping tool to refurbish a valve, said valve comprising a valve seathaving a valve seat angle and a diffuser passage having a diffuserangle, said lapping tool comprising: a body having a length greater thana width; said body having opposed first and second ends; said first endinsertable in a lapping unit for motion of the tool in an X axis, a Yaxis and a Z axis, said second end equipped with a head portion havingan abrasive surface; said head portion having an angled work portionhaving a first angle, and an angled end diameter portion having a secondangle, said angled work portion and said angled end diameter portionseparated by and contiguous with a radiused portion; said first angle ofsaid head portion substantially the same angle as said valve seat angle,and said second angle of said head portion substantially the same angleas said diffuser angle; and said radiused portion forming a radiusedintersection between said angled work portion and said angled enddiameter portion, said radiused intersection configured to facilitate achamfered cut at an intersection of said valve seat angle and saiddiffuser angle of said valve.
 6. The lapping tool of claim 5, whereinsaid body and said head portion are separated by a tapered portion. 7.The lapping tool of claim 5, wherein said abrasive surface includes atleast one of diamond, cubic boron, or silicon carbide abrasive having agrit in the range of about 30 microns.
 8. The lapping tool of claim 7,wherein said head portion comprises a nickel plated layer with said gritimpregnated in said nickel plated layer.
 9. An apparatus to refurbish aball check valve in a single operation, said ball check valve comprisinga valve seat having a valve seat angle and a diffuser passage having adiffuser angle, said apparatus comprising: a fixture configured toaccept said ball check valve; said fixture mountable in an precisionslide machining apparatus for movement of said fixture in an X axis anda Y axis; said fixture supported by a preloaded biaser to controlmovement of the fixture in a Z axis; a rotary power unit suitable torotate a lapping tool at various speeds; said lapping tool equipped witha body having a length greater than a width; said body having opposedfirst and second ends; said first end insertable in said rotary powerunit for motion of said lapping tool in an X axis, a Y axis and a Zaxis, said second end equipped with a head portion having an abrasivesurface; said head portion further comprising: an angled work portionhaving a first angle; an angled end diameter portion having a secondangle and protruding outward from said angled work portion, said angledend diameter portion having a proximal diameter and a distal diameter,said distal diameter shorter than said proximal diameter; said angledend diameter extending at said second angle from said proximal diameterto said distal diameter; said first angle of substantially the sameangle as said valve seat angle, and said second angle of substantiallythe same angle as said diffuser angle; and said angled work portion andsaid angled end diameter portion separated by and contiguous with aradiused portion, said radiused portion configured to form a chamferedintersection between said valve seat angle and said diffuser angle. 10.The apparatus of claim 9, wherein said apparatus is a ComputerNumerically Controlled (CNC) machine center.
 11. The apparatus of claim9, wherein said lapping tool further comprises a tapered portionseparating said body and said head portion.
 12. The apparatus of claim9, wherein said abrasive surface includes at least one of diamond, cubicboron, or silicon carbide abrasive having a grit in the range of about30 microns.
 13. The apparatus of claim 12, wherein said head portioncomprises a nickel plated layer with said grit impregnated in saidnickel plated layer.